Flexible tube having a variable stiffness bellows



FIG. 1 is a perspective view of a flexible tube having a stiffnessbellows showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a side elevational view thereof; and,

FIG. 4 is a sectional view taken along line 4—4 in FIG. 3.

The invention is illustrated in FIG. 1 where there is shown a flexibletube that includes a bellows having a plurality of convolutes formedtherein spaced at an interval from each other in the axial direction offlexible tube. The convolutes are raised circumferential ridges formedin the surface of the tube as an integral part thereof, have bendingsections that are approximately the same height above the outer surfaceof the tube and restrained elongation sections that are approximatelythe same height above the outer surface of the tube with the bendingsections having a height above the outer surface of the tube greaterthan the height of the restrained elongation sections above the outersurface of tube.

In FIG. 2, there is shown another embodiment of the invention which issimilar to that shown in FIG. 1, except that the shape of the convoluteshas been modified such that near the surface of the tube the convolutesare narrower in the area of the higher restrained elongation sections ofthe convolutes than in the area of the lower bending sections of theconvolutes, with the width of the convolutes being tapered moving fromthe bending sections to the restrained elongation sections.

Another embodiment of the invention is shown in FIG. 3, where there isshown a flexible tube as in FIG. 1, where the restrained elongationsections include two radially-spaced ridges which are attached at bothends to the bending sections of the convolutes.

FIG. 4 show a flexible tube of the invention similar to that of FIGS. 3except that the ridges formed in the convolute are tapered.

The ornamental design for a flexible tube having a variable stiffnessbellows, as shown and described.